Which minimizess the number of things you need to get right or in your words equals more secure.
Designing a token that can be validated instead of looked up. (Design/Implement once)
Or
maintaining, updating and monitoring a set of firewall rules so that app-servers in network zone x and y can make call backs to a database in network zone z.(design many implement many)
There are a ton of great reasons to use JWT at scale. As with anything use case is important.